If you are doing research on a product idea, how do you make sure that you are building something people want?
A great place to gather data for making early user personas is any kind of forums, groups or communities related to the idea.
See for example, that's where the idea for my Tables plugin for Adobe XD came from; a forum discussion of XD users who are frustrated about the lack of a table tool. You can feel their pain:
And after several iterations and development, here's a preview of the final plugin:
:)